Questions: Find the equation of the tangent line to the curve y=(3 ln (x)) / x at the points at the point (1,0) y= at the point (e, 3 / e) y=
Transcript text: Find the equation of the tangent line to the curve $y=(3 \ln (x)) / x$ at the points
at the point $(1,0) \quad y=$ $\square$
at the point $(e, 3 / e) \quad y=$ $\square$
Solution
Solution Steps
To find the equation of the tangent line to the curve \( y = \frac{3 \ln(x)}{x} \) at given points, we need to:
Compute the derivative of the function \( y \) to get the slope of the tangent line.
Evaluate the derivative at the given points to find the slope at those points.
Use the point-slope form of the equation of a line to write the equation of the tangent line at each point.
Step 1: Define the Function and Compute its Derivative
Given the function \( y = \frac{3 \ln(x)}{x} \), we first compute its derivative to find the slope of the tangent line. The derivative is:
\[ y' = \frac{d}{dx} \left( \frac{3 \ln(x)}{x} \right) = -\frac{3 \ln(x)}{x^2} + \frac{3}{x^2} \]
Step 2: Evaluate the Derivative at the Given Points
We need to find the slope of the tangent line at the points \((1, 0)\) and \((e, \frac{3}{e})\).
At the point \((1, 0)\):
\[ y'(1) = -\frac{3 \ln(1)}{1^2} + \frac{3}{1^2} = 0 + 3 = 3 \]
At the point \((e, \frac{3}{e})\):
\[ y'(e) = -\frac{3 \ln(e)}{e^2} + \frac{3}{e^2} = -\frac{3 \cdot 1}{e^2} + \frac{3}{e^2} = 0 \]
Step 3: Use the Point-Slope Form to Find the Tangent Line Equations
Using the point-slope form of the equation of a line, \( y - y_1 = m(x - x_1) \), we can write the equations of the tangent lines.
At the point \((1, 0)\) with slope \( m = 3 \):
\[ y - 0 = 3(x - 1) \]
Simplifying, we get:
\[ y = 3x - 3 \]
At the point \((e, \frac{3}{e})\) with slope \( m = 0 \):
\[ y - \frac{3}{e} = 0(x - e) \]
Simplifying, we get:
\[ y = \frac{3}{e} \]
Final Answer
The equations of the tangent lines are:
At the point \((1, 0)\):
\[ \boxed{y = 3x - 3} \]
At the point \((e, \frac{3}{e})\):
\[ \boxed{y = \frac{3}{e}} \]